Combined pump and motor assembly for liquid dispensing apparatus



Sept. 11. 1956 c. F. BATEMAN 2,762,306

COMBINED PUMP AND MOTOR ASSEMBLY FOR LIQUID DISPENSING APPARATUS 4 Sheets-Sheet 1 Filed Nov. 8, 1954 QNN NNN m W y v A O B n MM F M mMW m/ S m A O C Sept. 11. 1956 c F. BATEMAN 2,762,306

COMBINED PUMP AND MOTOR ASSEMBLY FOR LIQUID DISPENSING APPARATUS Filed Nov. 8, 1954 4 Sheets-Sheet 2 12 rm r;

INVENTOR.

COATES FAIF EEAX BATEMAN H/S ATTORNEY Sept. 11. 1956 c. F. BATEMAN 2,762,306

COMBINED PUMP AND MOTOR ASSEMBLY FOR LIQUID DISPENSING APPARATUS 4 Sheets-Sheet 3 Filed NOV. 8, 1954 INVENTOR COATES FAIRFAX BATEMAN H/S A T TORNEV Sept. 11, 1956 c. F. BATEMAN 2,762,306

COMBINED PUMP AND MOTOR ASSEMBLY FOR LIQUID DISPENSING APPARATUS 4 Sheets-Sheet 4 Filed Nov. 8, 1954 Ill I] 27 INVENTOR.

m U N Unite j. States Patent comn rnn PUMP AND MOTOR ASSEMBLY FoR LIQUID DISPENSING APPARATUS Coates Fairfax Bateman, Salisbury, MIL, assignorto Wayne Pump Company, Salisbury, Md, a orporatlon of Maryland Application November 8, 1954, Serial No. 467,291 7 Claims. (Cl. 1 03 42) The present invention relates to a combined pump and motor assembly mounted as an integrated unit in a unitary casing structure. More particularly, the present invention relates to a combined pump and motor unit which is adapted to force-feed a liquid from a source of supply to a dispensing mechanism including means for deaerating the liquid and for simultaneously cooling the driving mechanism. 7

As will be readily understood by those skilled in the art, a multitude of attempts have been made to provide increasingly efiicient pumping mechanisms which are especially adapted for use with gasoline dispensing appa ratus. In such prior endeavors, various unsuccessful at tem ts have been made to eflectively separate out air, which unavoidably mixes with gasoline in the storage chamber or other supply source and in the delivery'line's to the dispensing apparatus. Up to the present time, how ever, contemporary pumping mechanisms have provided only to a limited degree of success due to a failure to include an economical structural arrangement for positively deaerating the gasoline during flow.

Another distinct, but related, ineflicacy in prior art liquid dispensing apparatus of this type has been a failure to' effectively cool the conventional motor which is used to operate the dispensing pump whereby the useful life of the motor has been substantially reduced beyond-that" theoretically possible.

Applicant, on the other hand, has found that-by at:

ranging the pump and motor mechanisms within a novelcompartmented casing, both of the above-noted in'eflicacies can be successfully overcomein an economical and simplified structure. In particular, applicant hasdis'c'ow ered that the air which is commingled with the li ui'dde' sired to be pumped and'dispensed can be more effectively and readily separated by so controlling'its flow as to cool during the expulsion of the air from the driving motor the liquid.

It is accordingly a prime object of'the' invention to'p'ro' vide a combined pump and motor unit which inherently functions as an air separator and as a self-cooled structure. provide a pump and motor mechanism for use with gasoline dispensingv It is another object of the invention to apparatus of conventional types in which the motor is continuously cooled by contact with the dispensed gaso-" line during operation of the unit. Yet another object of the invention is the provision of a novel'casing structure for enclosing the pump and motor unit and having a compartmented arrangement providing a' three-fold air sep'a-' rating action.

connection with the annexed drawings in which: 7

Fig. 1 is a top plan view of the pump and motor mechanism of the invention,

Fig. 2 is an end elevation view Fig. 1,

Fig. 3 is a sectional view taken Fig. 1,

Other and distinct objects will become apparent from the description and claimswhich follow in along the line 2-2 of along the line 33 of float valve chamber,

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 1,

Fig. 5 is a sectional view taken along the line 55 of Fig. 1, V

Fig. 6 is a sectional view Fig. 3, and v Fig. 7 is a fragmentary view, partly in section, illustrating the relief valve mechanism controlling communi cation between the dispensing chamber and the inlet chamber.

Broadly, the invention comprises an integral casing as;- sembly, including a first dispensing chamber for housing driving motor, an inlet chamber adjacent to but isolated from said dispensing chamber and including structure for receiving liquid from a source of supply, a pumpcham ber communicating with said inlet chamber, a diffusing chamber communicating with said pump chamber and also communicating with said dispensing chamber, a first upper float valve chamber communicating with said diffusing chamber, and an air ejection or lower float valve chamber communicating with said upper float chamber and including a float valve associated with a return coriduit to said inlet chamber. A particular feature; of the invention is the provision of supplemental communicat'ion structure between the dispensing chamber and the upper float chamber providing a secondary air separation action. v p 7 Referring toFig. 1, it will be seen that the pump and motor mechanism of the invention includes a generally rectangular housing 19 provided with a pluralityof ho'rl z ontally extending mounting lugs or cars 11. The top: of the casing is provided with a first cover member 12 form inga removable closure for the upper float valve chamber, a second cover member 14 forming a removable closure member for the inlet chamber, and a third cover member 16 forming a removable closure member for an automatic control valve mechanism in an outlet conduit and which is to be described with more particularity hereinafter. This control valve is adapted to monitor dispensf ing of the liquid from the casing 10 througha'housing32 to an'outlet line 30. A drive shaft 21 projects from one side ofthe casing as an extension of an electric motor supportedwithin chamber 56 and casing 10 and held in position therein by a removable flanged support plate 18; The motor shaft carries a pulley 20 which is connected; via belting 22 to a driven pulley 24 supported on theen'd of a driven shaft 26 extending from within casingll) and" connected in a manner hereinafter appearing to drive the pump mechanism. J v

On the opposite side of the casing are mounted two re movable bearing plates 27 and 28, respectively. Plate 27' taken along the line 6-6 of serves to provide access to the by-pass valve aflordingbe hereinafter readily understood. A further outletc on 'duit 40 extends from another side of the casing and forms" separated from an escape passageway for the airwhichis u the liquid dispensed bythe unit. An additionalconduit 36 is provided on the motor support plate 18 for thepur wires to the' motor sup'f pose ofdirecting electrical lead ported withinthe casing proper. It will alsobe seen by reference to Fig. 2, which is a vertical'e'nd view 'of casing i 10,-that'it includes a removable cover-member 35'- for'rn ing a closure for the float valve mechanism in'th'e'lower as will be understood more readily hereinafter. An annular neck or lip 37 projects from the a removable closure plate providing access to the lower float valve charnber, aswill' casing wall adjacent to member 35 and forms a communication chamber for connection with a source of supply of the liquid desired to be dispensed by the unit. The novel structure of the invention will be better understood, however, by reference to the sectional views of the casing and combined motor and pump unit as illustrated in Figs. 3 to 6 inclusive. i

As illustrated most clearly in Fig. 3, the interior of casing 10 is divided into multiple, independent compartments to provide a plurality of chambers in a novel manner to obtain the results according to the invention. As shown in the figure, a first vertical wall 55 transverses the height of the casing, merging with the top and bottom walls, and dividing the easing into a first independent dispensing chamber 50 and a second adjacent inlet chamber '60. The chamber 60 is in turn enclosed by a further short vertical wall 65 which includes an integral, curved and horizontally extending roof-like portion 66. The wall and roof portions 65 and 66 cooperate with the right-hand end wall of casing 10 to form another independent compartment functioning as a lower float valve chamber 100. The curved roof portion 66 also serves as a floor for a conventional pump structure 72 carried by pump shaft 26 and together with an upper vertically extending web 75 which is an integral extension of wall 65, as will be appreciated from an inspection of Figs. 4, and 6, serve to isolate the suction and pressure sides of pump 72. Web 75 includes integral diverging arm portions 76 and 78 which further sub-divide the interior of casing into a pump chamber 70 and a difiusing chamber 80. It will thus be understood that walls 55, 65, 66, 75 and 78 serve to isolate the inlet chamber 60 from the remainder of the compartments in the chamber. This will be more readily appreciated by reference to Figs. 4 and 5 of the drawings which clearly show that wall 65 extends the length of the casing and is so configurated as to form, in conjunction with an integral laterally extending web 68 (see Fig. 5), a further isolated compartment functioning as an upper float valve chamber 90.

The inlet chamber 60 is in direct communication with pump 72 via an opening formed in the vertical wall 65 in the region of Web 75 and is in further direct communication with a return or pressure by-pass passageway 110 formed by an ofiset in the lower end of vertical wall 55. The inlet chamber directly opposes an opening in the bottom of the housing formed by the annular neck or lip 37 and is provided with an elongated hollow cylindrical strainer member 61 which is mounted to seat in a web 62 at the lower end of the housing and a further web 63 at the top of the housing. The arrangement is such that fluid entering the casing 10 via opening 37 will be directed into the elongated cylindrical strainer 61 before passing into the pump mechanism 72. The chamber 60 also is in free communication with a by-pass passageway 102 formed by an offset portion of wall 65 in cooperation with grooved channelways formed in the removable cover member 35. Passageway 102 terminates at one end intermittent opening 37 and strainer unit 61 and at its other end in a shoulder 103 forming a support for a valve seat 104 of a float valve mechanism 105.

The vertical extension 76 of web 75 terminates below the top wall of casing 10 forming a narrow egress passageway 79 between pump chamber 70 and the diffusing chamber 80. As will be more readily understood by reference to Fig. 3, the compartmentation of the casing is such that the liquid driven by pump 72 will rise in chamber 70 to flow over the upper lip of wall 76 and discharge into the difiusing chamber 80 where it will come into contact with a second elongated strainer unit 85 positioned to extend the length of chamber 80 and serving to block passage of the liquid from out of chamber 80. This second strainer unit comprises a diffusing member of known construction and which is so formed as to efiectively separate air from liquid, as for example, gasoline, by forcing the liquid to travel a longer path. After passage through 4 V the difluser 85, the fluid is permitted to discharge into the outlet or dispensing chamber 50, see Fig. 4, where the fluid will come into direct and intimate contact with outer casing of the enclosed motor (shown in phantom in the figures at 51) Dispensing chamber 50 is provided with a vertical uptake pipe 53 supported to depend to adjacent the floor of the housing from a removable valve seat member 54. The valve seat member is supported in an opening 56 in the top of the casing. A valve member 57 is carried within a housing 32 and is normally resiliently urged by means of a spring 58 to close ofi communication between pipe 53 and housing 32. The upper end of spring 58 is carriedby a recessed groove in the removable cover plate 16 which is normally secured to the housing as shown. As hereinbefore indicated, housing 32 is in direct communication with discharge line 30 via an internal passageway 34.

The vertical wall which separates chamber 50 from the remainder of the casing compartments includes an offset 69 (see Figs. 4 and 5) which rises to the top of the casing and in cooperation with the bell-shaped cover 12 serves to provide a supplemental air return passageway 92 between chamber 50 and the upper float valve chamber 90. It will be understood that the positioning of passageway 92 at the very top of the casing efiectively prevents the escape of the relatively heavy liquid normally present in chamber 50 while allowing air and air borne liquid vapors to find their way into the upper float valve chamher where it can accumulate and separate by a settling action.

The accumulated liquid in chamber is adapted to be returned to the lower float valve chamber through a passageway 91 connecting the two chambers and monitored by a float valve mechanism 95. The float valve mechanism includes a conventional float element 93 which is connected to a pivoted linkage structure 94 which supports a hollow, sleeve-like valve element 96. The sleeve 96 cooperates with a valve seat member 98 to block and unblock an underlying communication passageway 91. Valve element 96 includes a reduced diameter perforation or orifice at its lower end, as shown in the drawings at 97. The size of the opening 97 is so chosen that air which separates out from the liquid accumulated in chamber 90 can readily find its way through the hollow valve stem and the reduced diameter orifice 97 and thence through passageway 91 into the lower float valve chamber 100. The smallness of opening 97 is such, however, that liquid other than in vapor form cannot readily pass through the same whereby an efiective air separation action is allowed to take place. The float 93 and control linkage'94 is so arranged that valve 96 will be opened when the liquid level in chamber 90 is low to permit free egress of the liquid through passageway 91 into the lower float valve chamber 100. When the level of liquid accumulated in chamber 90 rises, however, now 96 blocks communication with passageway 91 and the accumulated liquid is forced to exit from the chamber slowly via a plurality of small orifices 99 provided in the valve seat adjacent passageway 91. It will thus be seen that air under such conditions must pass through orifice 97 independently of the liquid passing through orifice 99 whereby an effective separation action is obtained. Since orifice 97 is adapted to permit egress of liquid vapor from out of chamber 90, passageway 91 is surrounded by an elongated web 107 in order that the entrapped air in such vapors can be separated by forcing the vapor to follow a longer, downward path into chamber 100.

Referring now to Fig. 4 of the drawings, it will be seen that the liquid and air discharged into chamber 100 from passageway 91 is allowed to accumulate in the lower float valve chamber, providing an additional settling action and a further opportunity for effective eliminationof all included air from the liquid. The air which is thus separated is allowed to escape from the chamber via an greases outlet'conduit 40 positioned near the top of the chamber.

The liquid which accumulates in chamber 100 is adapted to be returned via the supplemental return passageway 102 to the inlet chamber 60, movement of the liquid being controlled by a second float valve construction 105. The float valve 105 includes the usual cylindrical float element 106 which is connected via a pivoted linkage structure 108 to areciprocating valve stem 109 positioned to selectively block and unblock communication with passageway 102. The arrangement is such that valve unit 105 normally blocks communication between chamber 166 and passageway 102 when the liquid level is low and float 106 is down. As the accumulated liquid rises, float .106 is raised and the valve opens, returning the liquid to the suction side of the pump.

As will be readily understood by those skilled in the art, the dispensing of fluid, such as gasoline, from chamber is controlled by means of a manually actuated valve cooperating with the conventional distributing nozzle of units such as gasoline pumping units. Accordingly, the check and pressure relief valve 57, 58 of Fig. 3 cooperates in the usual manner to control flow of fluid from out of chamber 50 through the line 30 in conjunction with such conventional manual control arrangement. However, under certain conditions it is desired that the device operate with the motor and pump working without dispensing the liquid from chamber 50 and for this purpose a bypass, pressure-controlled valve mechanism 120 is interposed in chamber 110 providing a return conduit between chamber 50 and the suction side of the pump at the inlet chamber 60. This valve arrangement will be better understood by reference to Fig. 7 of the drawings wherein it will be noted that the chamber 110 is formed to have an opening 59 supporting a valve seat structure 125 and which includes an inlet opening 121 and an outlet-portway 122. A valve stem element 123 mounting a control valve 124 is positioned in member 125 and is normally resiliently urged to a position where valve 124 closes off outlet portway 122 to block communication between the dispensing chamber and the inlet or suction chamber under the action of a spring 128 carried on a threaded stud 127. Stud 127 cooperates with a threaded sleeve 129 supported in the removable cover plate 27 and is provided with a slot 126 in its outer end whereby the tension of spring 128 may be readily adjusted to vary the setting at which valve 124 will open. It will thus be understood that valve unit 120 can be regulated to bypass liquid from the dispensing chamber to the suction side of the pump at any desired pressure obtaining in the dispensing chamber.

OPERATION Having generally disclosed the structure of the inven tion, reference will now be made to the operation of the same according to the mode contemplated in order to obtain the objects aforenoted. In order that the reader may better understand the invention, the operation of the unit will be described with respect to dry priming, wet priming, normal and by-passing conditions.

Dry priming When the pump and motor mechanism is first put into operation as when upon installation of the unit in an existing pumping station or upon starting the unit after a long period of inactivity there will be substantially no fluid in any of the casing chambers. As a result, the casing will be filled with air and upon energization of the motor 51, the pump 72 will draw air from the inlet or suction line 37 through the strainer 61, the inlet chamber 60 and the pump chamber and discharge it through the diffuser 85. As shown in Figs. 5 and 6, the air passing through the diffuser will rise to the top of the unit and. pass into the upper float chamber over the edge of. wall 73. Since the unit is substantially empty of liquid when the pump is initially started, float 93 in the'upper float chamber 90 and float 106 in the lower float chamber 100 are both in the lowermost or down position. When so positioned, the uppervalve 95 is open while the lower valve 105 is closed. As a result, the air entering the upper float chamber passes through the hollow valve stem 96 and the reduced orifice 97 into lowerfloat chamber 100 and is exhausted to atmosphere through the exit line 40.

As the pump begins to prime and-draw liquid into inlet 37, the new liquid will initially contain air and will be further mixed with air remaining in the suction and pumping chambers, as illustrated in the figure by arrows A. This air and liquid mixture is directed by the pump to follow the same path through the diffuser 85, which decreases the velocity of the liquid by reason of providing a long area over which the liquid must flow. This decrease in liquid velocity allows the air to separate from the liquid as both are discharged from the dilfuser into the motor chamber 50. The deaerated liquid flows over the motor 51, cooling it, as shown by arrows B in Fig. 4. The air thus separated rises to the top of the motorcha'mher and flows'through passageway 92 into the upper float chamber 90; Sincethe initial liquid discharged by the pump contains a considerable quantity of associated air, a substantial portion of the liquid discharged from the diffuser will rise with the air, as for example, as vapor or bubbles, shown in Figs. 4 and 5 by arrows C, and pass into the upper float chamber. This liquid accumulates in the upper float chamber and as its level rises becomes operative to raise float 93 to close valve 95, thus blocking thedischarge passageway 91 to the lower float chamber.

As previously'indicated, valve stem 96 includes a restricted orifice-97 which still provides egress for air from the upper float to the: lower float chamber. The air in the upper float chamber inherently rises above the liquid level i by reason of a pressure'diiterential and can pass through the hollow stem 96 and outlet orifice 97 into the lower float chamber from whence it is expelled from exit 40, as shown by arrow D in Fig. 4. It will be understood by those Skilled in the art that this automatic closing of the valve mechanism 95 servesto prevent accumulation of a larger amount of liquid in the lower float chamber than can be e'flicien'tly handled by the relatively small size thereof, and which has been found most desirable and convenient according to the present invention;

It will be further understood that a certain amount of the liquid discharged into the upper float chambers does pass through the restricted orifice and into the lower float chamber, where it is separated from the air. This liquid accumulates in the lower float chamber until its level rises a suflicient degree to raise float 106 and open valve 105. Upon the opening of valve 105, the accumulated liquid returns via passageway 102' to the suction side of the pump at the strainer 61. The action of float 106 is such that the lower valve will close as the liquid level drops preventing passage of air to the suction chamber, the liquid level at which float 106 opens Control valve 105 being so chosen in dependence upon the suction rate of pump 72 as to preclude inadvertent passage of airto the suction chamber through the return passageway 102, as by sudden cavitation, pulsation or the like.

Wet priming Under conditions in which the pumping unit has been regularly operated, the pump chamber 70 willnormally retain a suflicient amount ofliquid to facilitate selfprimin'g'. This condition will. still normally exist when the suction line 37 to' the unit is so positioned or located as to drain after a period of normal operation. This will be more readily understood by reference to Fig. 3' wherein the housing construction is such as to include a wall 65 between the pump chamber '70 and the inlet or suction chamber 60. It thus will be seen that under normal' conditions of operation, asubstantial amount of liquid will be left standing inthe internalgear pump. It will also be seen that some slight amount of liquid also shorter time.

will remain accumulated on the curved shoulder 66' of the dividing Wall 66 on the suction side of the pump. In

addition, a substantial quantity of liquid will remain in the liquid return passageway 102. The operation of the pump under these conditions takes place in an identical manner with respect to that described previously for a Normal -70 into the difluser 85. Here, as mentioned previously,

the liquid is given a decrease in velocity and any air present will rise and pass over into the upper float chamber '90, thence into the lower float valve chamber and ultimately through outlet 40.

The discharged liquid, free of air, enters the motor chamber 50 from the difluser. In this chamber, the liquid passes around the motor housing 51 (see Fig. 6) before entering the discharge pipe (see Fig. 3), and due to the location of the entrance to this pipe, the flow path of the liquid produces a continuous circulation all about the motor to prevent overheating. As chamber 50 fills, the liquid rises up the discharge pipe, through the check valve unit 57 and out the liquid outlet pipe 30.

The operation of the upper and low float valves during normal operation is the same as described previously. At the start of a cycle, the upper float. chamber is dry and the float controlled valve 95 is open since the liquid present in the chamber from the previous operation has drained, through the orifice 97 into the lower float chamher 100. The lower float chamber, on the other hand, will contain liquid, and the valve 105 is closed.

By-passing As will be readily understood, in some instances it will be desired to keep the motor energized and the pump operating without discharging liquid through outlet 30. Under such conditions the liquid pressure increases in cham ber 50 and soon reaches the level at which by-pass valve 124 is opened to its maximum position. With valve 124 open, the liquid from the motor chamber returns through the valve passageway 110 into chamber 60, around the strainer 61 and into the suction chamber adjacent the pump. Since the pump is still running, this liquid simply repeats its path and is recirculated until such time as the motor stops.

Since operating conditions will vary in different installations in which the unit can be utilized, the control pressure at which valve 124 opens is adapted to be easily varied by adjusting screw 127 which determines the force applied to the valve spring 128. Inspection of the drawings will show that the location of this by-pass valve is such that this adjustment can be readily accomplished in a minimum length of time by simply removing the cover 27. It will further be noted that the location of the bypass valve in the lower forward quarter of the motor chamber insures the continuous flow of liquid completely around the motor, therefore maintaining complete and full cooling of the motor, during the by-passing operation with the same efliciency as during normal operating conditions.

As many apparently widely difierent embodiments of this invention may be made without departing from the spirit and scope hereof, it is to be understood that this invention is not limited, except as defined in the appended claims.

What is claimed is:

1. In a combined motor-driven pump assembly having a supporting housing and including a dispensing chamber, a drive motor supported in said chamber, an inlet chamber adjacent to but isolated from said dispensing chamber and including structure receiving liquid from a source of supply, a pump chamber communicating with said inlet chamber, a pump mounted in said pump chamber, means extending externally of said housing for connecting said drive motor to said pump to operate the latter, a diffusing chamber communicating with said pump chamber and also communicating with said dispensing chamber, a difiuser element supported in said diffuser chamber, an upper float valve chamber communicating with said diffusing chamber and said dispensing chamber, a lower float valve chamber communicating with said upper float chamber and including an exit line for air separation purposes, float valve control means positioned in said upper chamber to partially block communication between said upper float valve chamber and said lower float valve chamber dependent upon the volume of liquid in said upper float valve chamber, and a return conduit establishing communication between said inlet chamber and said lower float valve chamber and including a float valve mechanism positioned in said lower float valve chamber and so constructed as to selectively block an unblock said return conduit dependent upon the liquid level in said lower float valve chamber, and an outlet conduit posihoned in said dispensing chamber in such manner as to direct liquid from said diflusing chamber around said motor to cool the same.

2. A combined motor-driven pump assembly as set forth in claim 1 in which said upper float valve mechanism includes a reciprocable hollow valve stem adapted to partially block the communication between said upper float valve chamber and said lower float valve chamber, said stem having a central perforation forming an orifice providing a constant egress path for the escape of air and vapors from said upper chamber to said lower chamber.

3. A combined motor-driven pump assembly as set forth in claim 2 in which said upper float valve mechanism includes at least one by-pass orifice providing constant communication between said upper float valve chamber and said lower float valve chamber, said by-pass orifice being of such dimension as to pass liquid slowly as compared with the float valve when in open position.

4. A combined pump and motor assembly for dispensing liquid in a deaerated condition comprising a compartmented casing, one compartment of which comprises a dispensing chamber, a second of which comprises an inlet chamber, a third of which comprises a pumping chamber, said dispensing chamber, inlet chamber and pumping chamber being physically positioned contiguous to each other, said inlet chamber being isolated from said dispensing chamber but being in open communication with said pumping chamber, a motor mounted in...

said dispensing chamber, a pump supported in said pump chamber, means externally of said casing for operatively connecting said motor to drive said pump, a diflusing chamber positioned above said pumping chamber and being so constructed and arranged as to be in free communication with said pumping chamber and said dispensing chamber, a diffuser element having means adapted to effectively separate air from liquid positioned in said diffusing chamber and blocking free communication with said dispensing chamber whereby fluid delivered from said pumping chamber must pass through said diffuser element before entering said dispensing chamber,

, outlet means positioned in said dispensing chamber in such manner as to cause liquid discharged from said diffuser to flow around and cool said motor, an upper float valve chamber positioned adjacent said diffusing chamber and said dispensing chamber and being so constructed as to be in free communication with said diflusing chamber and said dispensing chamber at a point adjacent the top of said housing whereby air which separates from the liquid pumped through said unit may pass from the diffusing chamber and the dispensing chamber into said upper float valve chamber, a lower float valve chamber positioned beneath said upper float valve chamber and including means communicating with said upper float valve chamber, an exit line in said lower chamber for exhausting air from said housing, a control valve positioned in said upper float valve chamber operative to partially block communication between said upper float valve chamber and said lower float valve chamber depending upon the liquid level in said upper float valve chamber, said control valve including a reduced diameter by-pass orifice constantly establishing communication between said chambers whereby liquid at a relatively low rate may pass to said lower float valve chamber, and means comprising a return conduit positioned between said lower float valve chamber and said inlet chamber.

5. A combined pump and motor assembly as set forth in claim 4 in which said control valve comprises a hollow valve stem and a float element connected to actuate said stem to partially block communication between said respective chambers as the liquid level in the said upper chamber rises, said valve stem including a reduced diameter orifice at its lower end adapted to provide constant communication for air and air-borne vapors from said upper chamber to said lower chamber when said valve is in closed position.

6. A combined pump and motor assembly as set forth in claim 4 including a second control valve structure having a float element operatively connected therewith positioned in said lower chamber and adapted to block and unblock communication between said lower chamber and said return conduit dependent upon the liquid level in said lower chamber.

7. A combined pump and motor assembly as set forth in claim 6 in which a pressure responsive by-pass is positioned intermediate said dispensing chamber and said inlet chamber, said valve being so constructed and arranged as to return liquid from said dispensing chamber to said inlet chamber upon the existence of a predetermined pressure in said dispensing chamber whereby said motor may be continuously operated and constantly cooled without delivering liquid through said outlet line.

References Cited in the file of this patent UNITED STATES PATENTS 1,920,066 De Lancey July 25, 1933 2,246,951 Peter June 24, 1941 2,330,634 Shoemaker Sept. 28, 1943 2,330,703 Grise Sept. 28, 1943 2,368,883 Roth Feb. 6, 1945 2,493,929 Rittenhouse et a1. Jan. 10, 1950 

